Semiconductors, or computer chips, are found in virtually every electrical product manufactured today. Chips are used not only in very sophisticated industrial and commercial electronic equipment, but also in many household and consumer items such as televisions, clothes washers and dryers, radios, and telephones. As products become smaller but more functional, there is a need to include more chips in the smaller products to perform the functionality. The reduction in size of cellular telephones is one example of how more and more capabilities are incorporated into smaller and smaller electronic products.
Typically, a plurality of individual chips are fabricated from a single wafer of substrate which incorporates individual subcomponents of the specific chip. The substrate can be a silicon or gallium arsenide substrate, or similar. The plurality of individual chips must be tested to determine whether the chips are good chips, repairable bad chips and non-repairable bad chips. Repairable bad chips can be laser repaired and retested. The good chips are singulated from the wafer into a plurality of individual chips. The chips are then packaged and again retested before they are shipped.
FIGS. 1a-1d depicts an example method of manufacturing a “bumped” semiconductor structure 10 which is tested for quality and reliability. A wafer 12 is first provided (FIG. 1a). The wafer 12 includes a bond pad 14 which is disposed over a top surface of the wafer 12. A water passivation layer 16 is disposed over the bond pad 14. Turning to FIG. 1b, an under bump metallurgy (UBM) 18 is disposed over the passivation layer 16. FIG. 1c depicts a solder ball 20 which is attached to the structure 10 and electrically contacts the UBM 18. Finally, turning to FIG. 1d, a probe needle 22 is utilized to carry out the testing process. Needle 22 comes into contact with the top of ball or “bump” 20 to provide electrical connectivity from ball 20 to needle 22 for the testing procedures.
By placing the needle 22 into contact with the top of bump 20 to conduct the testing as described in FIGS. 1a-1d, excessive bump 20 damage can result. The damage can ultimately result in electrical failure of the semiconductor structure 10. In addition, excessive bump 20 damage can also lead to problems such as internal voids which remain after the structure 10 is attached to a flip chip or similar semiconductor device.
Finally, solder “buildup”, which refers to a situation where solder sticks to needle 22, will also occur during the testing process of structure 10. The buildup of solder material on needle 22 contributes to subsequent bump 20 damage as the needle 22 makes contact with additional bumps 20 during contact testing.
As a result, a need exists for a bumped semiconductor structure which allows for testing with a conventional needle 22 without the necessity of needle 22 coming into contact with the top surface of bump 20. Accordingly, a need also exists for a method of manufacturing the bumped semiconductor structure which alleviates the previously described problems. The structure and method of manufacturing the structure should take manufacturing, cost and efficiency constraints into account.